When using diesel engines, air supply cut off valves are useful if it is desirable to quickly shutdown the engine for safety purposes. Such a condition under which it would be so desirable would be where there exist combustible substances about the engine as may be the case when oil or gas wells are drilled. Further, mechanical malfunctions may cause the engine to overspeed thus creating the potential for economic loss. This is obviously undesirable and engine cut off valves may be used to eliminate the possibility of such loss.
Engine shutdown valves are known. Such an engine shutdown valve is disclosed, for example, in our U.S. Pat. Nos. 4,215,845 and 4,285,495. These devices are satisfactory for the purposes under which they are used but they have the disadvantage in that they are too large for some applications.